The present invention generally relates to a communication system, and more particularly to a communication system which allows only an intended destination to appropriately receive a communication signal such as a control signal, a data signal, and so on.
A remote control system using radio communication technologies occasionally needs to make settings to enable a particular control apparatus (or initiator) to remotely control a target apparatus, and to disable other control apparatuses to remotely control the target apparatus. In such a case, as described in the following References 1 and 2, a control apparatus multiplexes in a control signal an ID signal for identifying a target apparatus, and transmits the resulting multiplexed signal, while the target apparatus obtains the control signal multiplexed with the own ID signal from received signals, and performs a control operation in accordance with the control signal.
The following Reference 3 describes a system for grouping apparatuses such as transmitters and receivers connected to a network. In this system, when an apparatus receives an infrared signal, the apparatus sends a signal to a control unit which communicates with other apparatuses, and the control unit determines on the basis of the signal received from the apparatus which group the apparatus belongs to, thereby enabling the apparatuses within the group to communicate.
Reference 1: Japanese Patent Public Disclosure No. 2003-47078
Reference 2: Japanese Patent Public Disclosure No. 2002-374582
Reference 3: Japanese Patent Public Disclosure No. 2003-37604
However, in the remote control systems described in References 1 and 2, it is necessary to preset an ID of each target apparatus for control in both a control apparatus and the target apparatus. Therefore, if a combination of a control apparatus with a target apparatus is relatively frequently changed, an ID must be set in the control apparatus and target apparatus each time the combination is changed. Also, even if a combination of a control apparatus with a target apparatus is fixed, when the control apparatus (or the target apparatus) is replaced with another one, the ID must be set again in the new control apparatus (or new target apparatus). Since repeated setting of an ID is time-consuming for an operator to perform, a need exists for a method of simply and automatically setting an ID each time a control apparatus or a target apparatus is replaced with another one.
The foregoing problem holds true not only in a remote control system comprised of control apparatuses and target apparatuses, but also in a general wired communication system and wireless communication system comprised of transmitters and receivers which communicate signals such as data in which an ID is multiplexed.
Therefore, in the following description, the terms “transmitter” and “receiver” refer to apparatuses for carrying out communications to each other, which include a “control apparatus (or initiator)” and a “target apparatus”, and the term “a communication system” refers to a wired or wireless system for carrying out communications, which includes a “remote control system.”
Further, in the system described Reference 3, apparatuses must communicate with one another to recognize those apparatuses which belong to the same group.